The present invention relates to a product in tape form for supporting, conveying and testing electronic components and to a process for producing it.
More particularly, the invention relates to such a product derived from the technology of assembling electronic semiconductor components which is known as T.A.B. (an abbreviation of the English expression "Tape Automated Bonding").
The T.A.B. technology is used to a great extent today for assembling integrated circuits in electronic devices when it is expedient for manufacture to be in large series or with a high production rate or to have components with a large number of outputs. This technology utilizes the principle of conveying parts mounted on tapes towards assembly stations. These tapes are produced so as to provide the chip with all its input/output connections, or "tabs", to the receiving circuit, the connections being formed in an electrically conductive layer of the tape by mechanical cutting out, photoetching or any other process, such as the laser-cutting process described in European Patent Application No. 130,498.
In particular, an alternative version of the T.A.B. technology, called "single-layer", is known, and in this a single metal tape provides both the support necessary for conveying the chips and the input/output connections of each chip. Since these connections are integral with the tape, it is expedient to separate them from this tape before carrying out the folding of the "tabs" and the installation of the chip in the receiving circuit. It will be noted that, before this separation, all the connections or "tabs" of the chip are short-circuited because of their connections with the metal tape. Under these conditions, it is not possible to conduct tests of the chip before the latter has been detached from the tape. However, it would be very convenient to carry out these tests when the chips are still integral with the tape.
There is a known process which involves molding on the chip and two electrically insulated test outputs, in order to keep the chip attached to the conductive tape. The chip can then be passed through a test appliance which ensures that the outputs of the chip are held in place and which is therefore not standard.
U.S. Pat. No. 4,480,150 and British Application No. 2,169,553 describe conveyor tape structures allowing tests on the chips carried by the tape. In particular, the abovementioned British application relates to such a structure using the T.A.B. technology. However, the structure provided is of the "three-layer T.A.B." type and cannot be transferred to a tape of the "single-layer T.A.B." type.
Now this last structure proves expedient and even indispensable in some uses, such as the T.A.B. assembly of power chips which implies the flow of relatively high currents in some connections. The considerable thickness of the conductive tape (at the present time 70 .mu.m or 105 .mu.m in single-layer T.A.B.) allows the passage of such currents higher than those acceptable in T.A.B. technology with two or three layers.